Why does illicit trade emerge, expand, and persist? This volume argues that the answer cannot be found in any single cause, actor, or level of analysis. Rather, illicit trade emerges through causal configurations in which motivations, opportunities, relationships, institutions, infrastructures, and broader structural conditions interact across different contexts.

Adopting an interdisciplinary, comparative, and causal approach, the volume examines these processes across micro, meso, and macro levels, connecting individual motivations and social relations with organisational networks, markets, legal and technological infrastructures, political conditions, conflict, migration governance, financial systems, and environmental pressures. It shows how illicit trade becomes attractive, possible, organised, scalable, tolerated, and resilient.

A central contribution of the volume is to distinguish the different functions that factors perform within causal processes. Some cause illicit trade by generating demand, incentives, pressures, or opportunities; others enable it by making illicit practices possible, scalable, or durable; still others facilitate it by reducing risk, concealing activities, or connecting actors. These roles are context-dependent, and illicit trade is frequently embedded in licit markets, institutions, infrastructures, and social relations.

Bringing together perspectives from law, criminology, economics, sociology, political science, international relations, migration studies, technology studies, environmental studies, and finance, the volume offers an integrated framework for scholars, policymakers, and practitioners seeking to understand why illicit trade persists.

This is the second volume of the GLITSS trilogy, a four-year collaborative endeavour involving nearly 300 researchers from 48 countries under the COST Action Globalization, Illicit Trade, Security and Sustainability (GLITSS).

Indrek Saar is an economist and working as Professor at the Financial College of the Estonian Academy of Security Sciences (EASS) and Associate Professor of Economics at the School of Governance, Law and Society (SOGOLAS) of Tallinn University. He leads a Working Group of the COST Action Globalization, Illicit Trade, Security and Sustainability (GLITSS) and the research group at EASS focusing on illicit trade in seaports. His main research interests and publications lie in the fields of public finance and illicit economies, including, among other topics, the development of tax gap measurement methodologies and the mechanisms underlying the functioning of illicit markets.

Daniela Irrera is Professor of International Relations at the School of Advanced Defence Studies, CASD, in Rome. She leads Working Group 2 of the COST Action Globalization, Illicit Trade, Security and Sustainability (GLITSS). She is Chair of the European Consortium for Political Research (ECPR) and member of the research committee of the European Union Knowledge Hub on Prevention of Radicalisation (EUKHPR). Her research focuses on non-state actors and their impact on global policies in the field of security, peacebuilding and humanitarian actions. She is author of NGOs Crisis Management and Conflict Resolution: Measuring the Impact of NGOs on Intergovernmental Organisations (Edward Elgar, 2013) and co-editor of Mapping Non-State Actors in International Relations (Springer, 2023) and has published widely on NGOs and humanitarianism, terrorism, organised crime, contractors.

Aleksandar Marsavelski, LL.M. (Yale), PhD (Freiburg/Zagreb) is Associate Professor of Criminal Law at the University of Zagreb, specializing in illicit trade, transnational crime, and political party crime. Since 2022, he has served as Vice-Chair of the COST Action Globalization, Illicit Trade, Sustainability and Security (GLITSS). A leading advisor to the Croatian Government and the Croatian Parliament on human trafficking and human rights, he has helped draft key criminal legislation, including the Criminal Code of Croatia (2009-2011). He regularly presents on illicit trade at global criminology forums.

Francesco Giumelli is Associate Professor of International Relations at the University of Groningen. He is Chair of the COST Action Globalization, Illicit Trade, Security and Sustainability (GLITSS) and Director of the Development, Security and Justice research theme at the University of Groningen. His research focuses on international sanctions, illicit trade, and the role of public and private actors in security governance. He is the author of International Sanctions (Il Mulino, 2023), The Success of Sanctions (Routledge, 2013), and Coercing, Constraining and Signalling (ECPR Press, 2011), and has published widely on sanctions, security governance, and international relations.